DE4025184A1 - Sensor detecting acceleration or inclination of motor vehicle - has metal anodes with protective oxide coatings in electrolyte in container forming cathode - Google Patents

Abstract

The sensor has at least one electrode (1,2) in a liquid in a container (4) forming a gravitation sensitive element. The electrode has a uniform, very thin protective oxide coating. The sensor has a container (6) forming a cathode and contg. at least one anode with protective coating and immersed in electrolyte (7). The metal anode pref. of Al or Ta with a coating of Al2O3 or Ta2O5. USE/ADVANTAGE - Esp. for use in motor vehicles, sensor is simple to mfr. and can be economically repaired if necessary.

Description

The invention relates to a sensor for Acquisition of acceleration or inclination, ins especially for motor vehicles with at least one elec trode in a in a closed container provided liquid as gravitational sensitive Element is added, the electrode with a Protective layer is coated.

A capacitive tilt sensor is already known (DE 37 44 411 C2), the gravi with a liquid tion-sensitive element in a closed Chamber works. The capacitor plates are with a highly insulating, solid passivation layer the same provided moderate thickness, the pre in the chamber seen liquid is electrically conductive, and the Chamber the counter electrode of the differential capacitor forms. With such an inclination sensor For example, damage the passivation layer once repair is very time-consuming and mostly economically no longer justifiable.

In contrast, the invention is based on the object train the sensor so that it is simple Manufactured wisely and inexpensively if necessary can be repaired. The task is solved according to the invention in that the on the electrode formed insulating layer formed as an oxide layer is. Such a layer can be very simple, inexpensive way to manufacture by the Immerse the electrode in an appropriate liquid is so that there is an oxide layer on the electrode can form with semiconductor property. Will one  such layer once for some reason destroyed, this can be at any time Restore reforming. This way the electrode is always in the assembled state repair. For this purpose, it is advantageous that the Electrode (anode) is coated with the oxide layer. It is also advantageous that the sensor as a Has cathode trained container in which at least one anode in an electrolyte is an oxide layer on the anode can be formed.

An additional possibility is according to a further development of the device according to the invention that the anode consists of a metal, in particular AL or Ta, and is preferably coated with an Al ₂ O ₃ or a Ta ₂ O ₅ layer. According to a particular feature of the solution according to the invention, it is finally seen that two or more identical anodes are accommodated in the container. It is also advantageous to use a solvent, in particular N, Ni-dimethylformamide, butyrolactone, dimethyl sulfide, a glycol-based liquid, or a mixture of these liquids or dilute sulfuric acid as the electrolyte.

In a further embodiment of the invention, it is advantageous adheres that the anodes have a circular cross-section exhibit. It is also possible that the anodes have a rectangular cross section and at least one Have stop surface. The electrodes can too be designed as spirals or a U-shape exhibit. This makes the anodes very easy position in the container. It is also for this advantageous that the anodes above the bottom plate  are additionally fixed by means of a holder. On this way you get a perfect fit for the Anodes. It is also advantageous that the anodes above the base plate in the area of its upper ends supported in the holder provided in the container are. It is appropriate that the bottom plate as Insulating body is formed on his Outer circumference a groove-shaped depression Crimping the outer wall of the container, being between the inside of the outer wall and the Depression a sealing element is provided.

It is also advantageous that by changing the Holder preferably in a crossed grid or U-tube achieved additional damping of the system becomes.

Another possibility of damping is realized by looking at the surface of the conductive liquid puts on a damping element.

To design this damping option preferably a plate, a grid, a net or a suitable liquid is used.

An additional option is according to one more formation of the device according to the invention that the Electrodes are coated with the dielectric so that a high dielectric constant is achieved. Further the surface is opposed by means of the oxide layer the liquid is very dense and particularly even locked.  

According to a special feature of the invention Solution, it is advantageous that two monostable tilt stages are provided, and the capacity values of the Sensors the time constants of the monostable flip-flops determine. Furthermore, one output is one monostable multivibrator with a set input (trigger Input) of the other monostable multivibrator connected that one by a transition monostable multivibrator in the stable state different monostable multivibrator in the unstable State is set.

An additional option is according to one more formation of the device according to the invention that the off gears of the monostable flip-flops with the set inputs are connected by differentiators and that Output signal of at least one monostable multivibrator can be fed to an integrator. It is also an advantage liable that the output signals of the monostable Kippstu fen an integrator can be fed and that the off of the integrators with inputs of a subtractor circuit are connected.

The device according to the invention has, among other things Advantage that the output signal is a monostable Flip-flop directly a first integrator and inverted can be fed to a second integrator and that the off of the integrators with inputs of a subtractor circuit are connected. It is also advantageous that the vibration is at least one monostable Flip-flop is monitored, and in the absence of Vibration over at least one monostable multivibrator the respective set input again in the stable State set and by a logical OR  Linking the two output signals of the monostable Flip-flops the oscillation of the circuit is monitored.

An additional option is according to one more formation of the device according to the invention that the Dif ferenzierglieder from one capacitor and one each connected to a connection for the operating voltage resistance exists and that both connections of the capacitors belonging to the differentiators connected to a resistor via a diode are, whose connection facing away from the diodes with Ground potential is applied. Other advantages of sensors according to the invention are the symmetrical structure, a high capacity change that is an easy one Evaluation circuit enables a large temperature rich, a linear characteristic, very low temper dependence on nature and good electromagnetic Compatibility.

The mentioned advantages of the sensor according to the invention enable in particular use in one Motor vehicle. However, the application is not on limited this purpose, but can for example also take place in aircraft and watercraft.

An advantageous embodiment of the invention Sensor consists of two electrodes in parallel run to each other and about half their length are covered with liquid. Preferably there is provided that the housing is in the form of a cup points. This version enables a particularly com compact component that is particularly inexpensive, if the housing is a commercially available capacitor cup is.  

It is also advantageous that the untreated Electrodes as standard components from the capacitor production can be taken, and thus in the Manufacturing and procurement are particularly inexpensive.

It is particularly advantageous that the sensor element preferably by soldering onto the circuit board Evaluation electronics can be applied and thus a compact and inexpensive construction of the sensor is achieved.

For measuring acceleration or inclination in several According to a further development of the Invention provided multiple anodes in the same housing will. However, it is not excluded for measurement acceleration in several directions for each one direction a sensor with two electrodes to provide.

The liquid for the arrangement according to the invention must be conductive, have low adhesive forces and a slight change in viscosity and volume expansion over temperature. It is also important that the Liquid has a low melting point and one has a high boiling point and is not aggressive towards it the materials used. Furthermore, it is advantageous if the temperature dependence of the Conductivity is low.

It is particularly advantageous that the oxide layer is very uniform and thin, approximately 1 μm and less, so that very high capacitance values result. Due to the high dielectric constants of Al ₂ O ₃ and Ta ₂ O ₅ , high basic capacities are achieved. This results in a large signal swing and, due to the uniformity of the layer, a particularly good linearity of the sensor.

The dielectric or the oxide layer with semiconductor property is insulating and unidirectional is easily created by forming. Should the oxide layer is destroyed when the sensor is assembled , it can be reformed at any time be restored.

The evaluation unit is characterized by a small Effort and generates a binary output signal that in a simple way by both a microprocessor also with the help of a simple analog circuit can be processed. Another advantage is there in that information on a signal line both sensor sizes are output. However, it can also a symmetrical output of the evaluation circuit be used, which is a good electromagnetic ver leads to inertia.

Circuits from two to each other in the unstable Swing state-setting monostable flip-flops after a malfunction, e.g. B. by a short circuit of the output signals, may not reappear. Around a safe one even in such a case To enable them to start again Evaluation circuit are further developed in that the differentiators a capacitor and each one at a connection for the operating voltage connected resistance exist around both Connections of those belonging to the differentiators Capacitors via a diode with a resistor  are connected, the one facing away from the diodes Connection is applied to ground potential.

Further features of the invention are in the description of the figures, it being noted that all Individual characteristics and all combinations of individual characteristics paint are essential to the invention.

In the figures, the invention is an embodiment Form shown, for example, without this off leadership form to be limited.

It shows:

Fig. 1 is a schematic representation of the way we act as a sensor for detecting the acceleration or the inclination.

Fig acting. 2 shows the sensor with two electrodes (anode), which are coated with an oxide layer as a dielectric,

Fig. 3 shows a second embodiment of a sensor,

Fig. 4 shows a third embodiment of a sensor with a holder for fixing the electrodes,

Fig. 5 is a sectional view of an electrode along the line 5-5 of FIG. 9,

Fig. 6 is a view of the sensor from below, according to Fig. 3,

Fig. 7 shows the output signals of the monostable multivibrators,

Fig. 8 is an equivalent circuit diagram of the execution example,

9 shows various embodiments. An anode,

Fig. 10 guide form a circuit diagram of a first stop,

Fig. 11 is a circuit diagram of another form imple mentation of the evaluation circuit shown in FIG. 12,

Fig. 12 is a block diagram of an evaluation circuit for the sensor according to the invention,

FIG. 13a to 13d different ways from the output signals an evaluation circuit which is located in the immediate vicinity of a sensor processing circuit to a proces transmitted to,

Fig. 14 shows a fourth embodiment with a modified holder for damping of the system,

Fig. 15 AB-sectional view of FIG. 14,

Fig. 16 shows a fifth embodiment with a further possibility of attenuation by modification of the holder,

Fig. 17 AB-sectional view of FIG. 16,

Fig. 18 shows a sixth embodiment with applied plate for damping,

Fig. 19 AB-sectional view of FIG. 18 and FIG. 18 deviating plate,

Fig. 20 AB-sectional view of FIG. 18 with a further embodiment of a plate.

In the schematic illustration of FIG. 1, two circular, elongated electrodes with a 1.2 shown in Fig. 5 dielectric 2 are coated a, immersed in an electrically conductive liquid 7. A acting on a container 4 in the direction of arrow acceleration a causes an inclination of the liquid level by the angle α. As a result, the electrode 1 is only covered with liquid 3 up to the height h ₁ , while the liquid 3 rises to h ₂ at the electrode 2 . The mean liquid level is (h ₁ + + h ₂ ) / 2. As can be seen from the triangle of forces also shown in FIG. 1, for the angle α tanα = F _m / F _g , where F _{m is} the inertial force counteracting the acceleration force F _a and F _{g is} the weight force.

The dielectric on the electrode surface forms a capacitor between the electrodes 1 , 2 and the conductive liquid, which is shown schematically in FIG. 2. The capacitance of such a coaxial capacitor results from:

C = [2πε₀ε _r / (ln (D / d))] · h

D is the outer diameter of the dielectric, d is the diameter of the electrode and h is the height of the respective electrode covered by the liquid 3 .

The difference in the capacities is then:

C₂ - C₁ = [2πε₀ε _r / (ln (D / d))] · (h₂ - h₁)

As can easily be derived from the triangle shown in FIG. 1, h ₂ -h ₁ = s · (a / g), where a is the acceleration transverse to the gravitational acceleration g and s is the distance between the electrodes 1 , 2 . The overall result for the normalized acceleration is then:

a / g = (C₂ - C₁) · (ln (D / d)) / (2πε₀ε _r s)

It can be seen that the value a obtained by measuring the capacitance difference a is independent of the fill level (h ₁ + h ₂ ) / 2, but is dependent on ε. In the evaluation, however, there is the possibility, according to a further development of the invention, of dividing the difference by the sum of the capacitance values. Then there is for the normalized acceleration

a / g = (C₂ - C₁) · (C₂ + C₁) · (h₁ + h₂) / s.

The measurement result is independent of ε, but from depending on the level. This has, for example Advantage that a temperature dependence of ε is not in the measurement result is received.

The sensor is based on an electrolytic capacitor. At least one anode 1 is located on the lower part or the base 5 . Two, three, four or more anodes can also be arranged on the bottom. In the embodiment shown in Fig. 3, the two electrodes 1 , 2 are held by the bottom 5 of a housing 6 available for capacitors. The metal housing 6 forms the cathode, while the electrodes 1 , 2 represent the anodes in the exemplary embodiments. The metal housing, which represents the cathode 6 , can be provided with insulation 8 .

In order to isolate the electrodes from the housing, the base 5 is formed entirely from Teflon or from another insulating material.

The housing or the container 4 is to be provided in the region of the bottom 5 with an annular recess 11 , into which the lower wall part of the container 4 is crimped and which serves to receive a sealing element or an annular seal 11 a. The ring seal 11 a can be received in an annular groove 11 b. Furthermore, the upper ends of the anodes 1 , 2 are additionally supported and fixed in the bores of a holder 10 . So that the installation heights of the anodes 1 , 2 are always the same, they have a stop 26 at the lower end, which rests on the surface of the base 5 . Furthermore, it is possible to hermetically seal the housing by soldering by appropriately redesigning the base 5 .

The liquid or electrolyte 7 covers approximately half of the electrodes or anodes 1 , 2 . The extensions of the electrodes 1 , 2 , which extend through the base 5 serve at the same time as solder pins 12 . A third solder pin 13 is arranged directly on the housing bo 5 and connected to the housing 6 according to FIG. 6 via a tab 13 a. The solder pin 13 forms the common counter electrode. The tab 13 b can also be connected directly to the top of the housing 6 according to FIG. 2.

The anodes 1 , 2 are formed, for example, from a metal, in particular from Al or Ta, and are preferably coated with an Al ₂ O ₃ or a Ta ₂ O ₅ protective layer or an oxide layer 2 a. The dielectric with semiconductor properties has an insulating effect in only one direction and is generated by forming. Depending on the requirements, the layer thickness can be less than 1 μm and is applied very uniformly to the surface of the anodes 1 , 2 . High layer capacities are achieved by layer thicknesses of less than 1 µm of the dielectric and by the high dielectric constants of Al ₂ O ₃ and Ta ₂ O ₅ . This in turn results in a large signal swing of the encoder when acceleration or inclination occurs. If the surface of the anode is damaged during assembly of the sensor, the damaged surface can be restored at any time by reforming.

The liquid 7 used should have low ash forces, low viscosity and volume expansion. In addition, it is necessary that the liquid have a low melting point and high boiling point and is not aggressive to the materials used. Furthermore, the temperature dependence of the conductivity should be low.

Solvents such as N, N- Dimethylformamide, butyrolactone, dimethyl sulfide, a Glycol based liquid, a mixture thereof, or dilute sulfuric acid can be used.

The solder pins 11 to 13 are arranged in a standardized grid, so that the sensor can be mounted directly on a circuit board. If necessary, the sensor shown in FIG. 1 can be used with the connections 11 to 13 directed upwards. As a result, the area where the electrodes 1 , 2 pass through the housing base 5 is not covered with the liquid 3 , so that the sealing points and the housing base 5 are not constantly loaded by the liquid 3 .

Fig. 8 shows an equivalent circuit diagram of the sensor according to the invention, which consists of two capacitors with capacitances C ₁ and C ₂ , which depend on the acceleration acting on the sensor Be according to the above derivatives.

In the circuit shown in Fig. 12, two monostable multivibrators 14 , 15 are provided, which are designed such that the duration of the unstable state is proportional to a variable X ₁ or X ₂ present as a resistance or capacitance value, which in the present case the Capacitance values correspond to C ₁ and C ₂ . Via a differentiator 16 , 17 or 18 , 19 , the outputs from the monostable multivibrators 14 , 15 are each connected to an inverting set input (hereinafter called trigger input) of the other monostable multivibrator. As a result, one monostable flip-flop is set to the unstable state when the other returns to the stable state.

At the outputs 20 , 21 of the monostable Kippstu fen 14 , 15 there are then rectangular signals, the course of which is shown in Fig. 7. The two time periods t ₁ and t _{2 are} each proportional to the input variables X ₁ and X ₂ .

If the difference between the variables X ₁ and X _{2 is} evaluated, a reduction in temperature sensitivity is obtained in the event that both variables have the same temperature response. However, this only applies to the zero point stability. To reduce the temperature response of the slope, it must be divided by the temperature-dependent variables. Such a signal is obtained in a simple manner in the evaluation circuit according to the invention by subtracting the mean values as follows: U _A1 -U _A2 = U _B (X ₁ -X ₂ ) / (X ₁ + X ₂ ).

In most sensors, in particular those in which high resistance values or small capacitance values (as in the sensor according to the invention) are evaluated, the evaluation circuit is located directly at the resistors or capacitors, while a device which processes the output signals of the evaluation circuit via one or more lines is connected to the evaluation circuit. The output signals of the evaluation circuit according to FIG. 12 form a good basis for transmission to the further processing circuit, for example a control unit in a motor vehicle. Depending on the requirements in detail, the transmission from the evaluation circuit to the control device can take place in the form of a binary signal or in the form of an analog signal.

Fig. 13 illustrates several circuit arrangements. In FIG. 13 a, one of the output signals U _A1 is transmitted in unchanged form, that is to say in binary form, by an evaluation circuit 37 . A digital computer 28 is provided on the receiver side, with the aid of which the times t ₁ and t _{2 are} measured, as a result of which the values X ₁ and X _{2 are} recovered. In the digital computer 28 , a difference, sum and quotient formation can then be carried out in a simple manner, so that a variable (X ₁ - X ₂ ) / (X ₁ + X ₂ ) arises, which, in the case of sensors, the output variable of which Difference between the two variables X ₁ and X _{2 is} formed, but X ₁ and X _{2 are subject to} an interference - for example a temperature-dependent speed.

In the circuit shown in FIG. 13b, the binary signal U _{A1 is also} transmitted. However, the further evaluation takes place with the aid of an analog circuit, which consists of an input amplifier 29 , an inverter 30 , two integration elements 31 and 32 or 33 and 34 and a differential amplifier 35 . Through the integration with the help of the integration element 31 , 32 , the mean value of the signal U _{A1 is} formed, which is proportional to X ₁ / (X ₁ + X ₂ ). The mean value of the inverted signal is formed by the integration element 33 , 34 and corresponds to X ₂ / (X ₁ + X ₂ ). The differential amplifier 35 then forms the desired result, which is present at the output 36 as an analog signal.

While the circuit shown in FIG. 13b represents an asymmetrical binary interface between the output of the evaluation circuit 37 and the input of the control device, the circuit shown in FIG. 13c has a symmetrical binary interface. For this purpose, both outputs of the evaluation circuit 37 are connected via a line to input amplifiers 29 , 38 of the control device. The analog signal is formed via integration elements 31 , 32 or 33 , 34 and a differential amplifier 35 , as in the circuit arrangement according to FIG. 13b. The advantage is interference immunity when transmitting over long lines.

Finally, FIG. 13d shows another possibility of signal transmission between an evaluation circuit and a control unit in which an analog signal is transmitted. For this purpose there are integration elements 22 , 23 and 24 , 25 and a dif ferential amplifier 39 in the area of the evaluation circuit 37 . The connection to the control device then takes place via a line 40 .

In the circuit arrangement shown in FIG. 10, the two monostable multivibrators 14 , 15 are formed by an integrated module from the 556 series (double timer circuit). As in the block diagram of FIG. 12, the outputs are each connected via a differentiator 16 , 17 or 18 , 19 to the inverting trigger input of the other monostable multivibrator. Resistors 41 and 42 are connected between the terminal 43 of the operating voltage U _B and the respective output and serve as Ar resistors. The inverting trigger inputs are each connected via a diode 44 , 45 to the terminal 43 to limit the voltage at the trigger inputs.

The inputs Dis and Thr of the monostable Kippstu fen 14 , 15 are each connected to a time constant element, each consisting of a resistor 46 , 47 and a capacitor 48 , 49 with variable capacitance. The capacitors 48 , 49 belong to the sensor, in which the capacitances are changed in opposite directions depending on the size to be measured. As already explained in connection with FIG. 12, the duration of the respectively unstable state is proportional to the capacitance, as a result of which the output signals U _A1 and U _A2 arise at the outputs of the monostable multivibrators 14 , 15 in accordance with the diagram shown in FIG. 7.

The circuit arrangement shown in Fig. 10 only swings when the rate of increase of the operating voltage when switching on exceeds a predetermined value. In the event of a brief interruption in the oscillation, for example due to a short circuit or the action of an interference pulse, the circuit does not start up again. In order to enable a safe start-up, the circuit arrangement shown in FIG. 11 is advantageously developed over the circuit arrangement according to FIG. 10.

For this purpose, the outputs of the monostable Kippstu fen 14 , 15 via a diode 51 , 52 and a common resistor 53 ge connected to ground potential.

The diodes 51 , 52 act as an OR combination of the signals U _A1 and U _A2 . Due to the fact that U _A1 and U _{A2 are} inverted from each other, the voltage U ₅₃ across the resistor 53 U _{B is} -0.7 V at all times when the circuit is oscillating. A capacitor 54 smoothes any peaks that occur during the edges of U _A1 and U _A2 arise.

If there is no oscillation, the output voltages U _A1 and U _{A2 are} at ground potential and both diodes 51 , 52 block. The voltage U ₅₃ and the voltages at the trigger inputs are then determined by the resistors 17 , 19 , the then conductive diodes 55 , 56 and the resistor 53 . The voltages at the trigger inputs thus fall to the value U _tr = (U _B - 0.7 V) / (1 + R ₁₇ / R ₅₃ ) +0.7 V. By selecting the values R ₁₇ and R ₅₃ of resistors 17 and 53 , U _{tr is set} below the value specified in the data sheet of the monostable multivibrator. This means that both output signals go back to the unstable state and the starting aid performed with the diodes is ended.

In addition to their function as starting aids, the diodes 55 , 56 also serve to limit the voltages to the trigger inputs, so that they do not rise above the operating voltage U _B. The dimensioning of the resistors 17 or 19 and 53 takes place according to the equation:

R _{17 (19)} / R₅₃ (U _B - 0.7 V) / (U _tr - 0.7 V) - 1,

with U _B = 5 V and U _tr 1.26 V. When using module 556.

This results in R _{17 (19)} / R₅₃6.68. In a practical circuit arrangement, R₁₇ = R₁₉ = 47 kOhm and R₅₃ = 6.8 kOhm was chosen.

The differentiators 16 , 17 and 18 , 19 have the task of deriving a short pulse, which characterizes the falling edge of the respective output signal.

This requires a time constant that is significantly less than the duration of the unstable states of the monostable multivibrators. This results in the following condition: R ₁₇ · C ₃ «R ₄₆ · C ₄₈ , which also applies analogously to elements 18 , 19 , 47 and 49 .

According to the exemplary embodiment according to FIGS. 14, 15, the holder 10 a can be designed in the form of a crossed grid for damping the system. Furthermore, it is possible ( FIGS. 16, 17) to design the holder in the form of a U-tube 10 b for damping the system.

In a further exemplary embodiment according to FIGS. 16, 17, a plate 57 a, 57 b, a grid or a network or a liquid is used for damping the system.

Reference list

1 electrode, anode
2 electrodes, anode
2 a protective layer oxide layer
4 containers
5 floor
6 cathode
7 electrolyte fluid
8 insulating layer
10 bracket
10 a crossed grid
10 b U-tube
11 deepening
11 a ring seal
11 b ring groove
12 solder pin
13 solder pin
13 a tab
13 b tab
14 flip-flop
15 flip-flop
16 differentiator
17 differentiator
18 differentiator
19 differentiator
20 exit
21 exit
22 integrator
23 integrator
24 integrator
25 integrator
26 stop
28 digital computers
29 input amplifiers
30 inverters
31 integrator
32 integrator
33 integrator
34 integrator
35 Subtracting circuit differential amplifier
36 exit
37 Evaluation circuit
38 input amplifiers
39 subtraction circuit
40 line
41 resistance
42 resistance
43 connection
44 diode
45 diode
46 resistance
47 resistance
48 capacitor
49 capacitor
51 diode
52 diode
53 resistance
54 capacitor
55 diode
56 diode
57 plate
57 a plate
57 b plate

Claims (24)

1. Sensor for detecting the acceleration or inclination, in particular for motor vehicles with at least one electrode ( 1 , 2 ) which is received in a liquid provided as a gravitationally sensitive element in a closed container ( 4 ), the electrode ( 4 ) having a Protective layer coated is characterized in that the layer ( 2 a) formed on the electrode ( 1 , 2 ) is formed as an oxide layer. 2. Sensor according to claim 1, characterized in that the electrodes (anodes 1, 2) with a uniform and very thin oxide layer ( 2 a) are pulled over. 3. Sensor according to claim 1 or 2, characterized in that the sensor has a cathode ( 6 ) formed container ( 4 ) in which at least one anode ( 1 , 2 ) is received in an electrolyte ( 7 ) by means of an oxide layer is formed on the ano de ( 1 , 2 ). 4. Sensor according to one or more of the preceding claims, characterized in that the anode ( 1 , 2 ) consists of a metal, in particular Al or Ta, and preferably, coated with an Al ₂ O ₃ or a Ta ₂ O ₅ layer is. 5. Sensor according to one or more of the preceding claims, characterized in that two or more approximately identical anodes ( 1 , 2 ) are accommodated in the container ( 4 ). 6. Sensor according to one or more of the preceding claims, characterized in that the electrolyte ( 7 ) is a solvent, in particular N, N-dimethylformamide, butyrolactone, dimethyl sulfide, a liquid based on glycol, a mixture of these liquids or dilute sulfuric acid. 7. Sensor according to one or more of the preceding claims, characterized in that the anodes ( 1 , 2 ) have a circular cross section. 8. Sensor according to one or more of the preceding claims, characterized in that the anodes ( 1 , 2 ) have a cross section with at least one stop surface. 9. Sensor according to one or more of the preceding claims, characterized in that the anodes ( 1 , 2 ) by means of an Isolierele element ( 8 ) in a container ( 4 ) provided base plate ( 5 ) is received. 10. Sensor according to one or more of the preceding claims, characterized in that the anodes ( 1 , 2 ) above the base plate ( 5 ) by means of a holder ( 10 ) are additionally supported and fixed abge. 11. Sensor according to one or more of the preceding claims, characterized in that the anodes ( 1 , 2 ) above the base plate ( 5 ) in the region of their upper ends are supported in the holder provided in the container ( 4 ). 12. Sensor according to one or more of the preceding claims, characterized in that the base plate ( 5 ) is designed as an insulating body which has on its outer circumference a groove-shaped depression ( 11 ) for crimping the outer wall of the container ( 4 ), wherein between the Inside of the outer wall and the recess, a sealing element ( 11 a) is provided. 13. Sensor according to one of the preceding claims, characterized in that the anode ( 1 , 2 ) is coated with a dielectric such that a high dielectric constant is achieved and the surface is sealed very tightly and evenly from the liquid by means of the oxide layer. 14. Sensor according to one of the preceding claims, characterized in that for damping the system, the holder ( 10 ) is designed in the form of a crossed grating ( 10 a). 15. Sensor according to one of the preceding claims, characterized in that for damping the system, the holder ( 10 ) is designed in the form of a U-tube ( 10 b). 16. Sensor according to any one of the preceding claims, characterized in that a plate ( 57 a, 57 b), a grid, a network or a suitable liquid is used to dampen the system. 17. Sensor according to one of the preceding claims, characterized in that two monostable multivibrators ( 14 , 15 ) are provided, that the capacitance values of the sensor determine the time constants of the monostable multivibrators ( 14 , 15 ) and that in each case an output of a monostable multivibrator with a set input (Trigger input) of the other monostable multivibrator is connected in such a way that a respective monostable multivibrator ( 14 , 15 ) in the stable state sets the other monostable multivibrator ( 15 , 14 ) into the unstable state. 18. Sensor according to one or more of the preceding claims, characterized in that the outputs of the monostable multivibrators ( 14 , 15 ) are connected to the set inputs via differentiators ( 16 , 17 ; 18 , 19 ). 19. Sensor according to one or more of the preceding claims, characterized in that the output signal of at least one monostable multivibrator ( 14 , 15 ) an integrator ( 22 , 23 ; 24 , 25 ) can be supplied. 20. Sensor according to one or more of the preceding claims, characterized in that the output signals of the monostable Kippstu fen ( 14 , 15 ) each an integrator ( 22 , 23 ; 24 , 25 ; 33 , 34 ) can be fed and that the outputs of the Integrators are connected to inputs of a subtractor circuit ( 35 , 39 ). 21. Sensor according to one or more of the preceding claims, characterized in that the output signal of a monostable flip-flop ( 14 ) directly to a first integrator ( 31 , 32 ) and inverted a second integrator ( 33 , 34 ) can be supplied and that the outputs the integrators are connected to inputs of a subtractor circuit ( 35 ). 22. Sensor according to one or more of the preceding claims, characterized in that the vibration of at least one monostable multivibrator ( 14 , 15 ) is monitored, and in the absence of vibration at least one monostable multivibrator ( 14 , 15 ) back into via the respective set input the stable state is set. 23. Sensor according to claim 19, characterized in that the logic of the circuit is monitored by a logical OR combination of the two output signals of the monostable tilting stages ( 14 , 15 ). 24. Sensor according to one or more of the preceding claims, characterized in that the differentiators each consist of a capacitor ( 16 , 18 ) and one connection ( 43 ) for the operating voltage connected resistor ( 17 , 18 ) and that both connections the capacitor s ( 16 , 18 ) belonging to the differentiators are each connected via a diode ( 51 , 52 , 55 , 56 ) to a resistor ( 53 ), the terminal of which is turned away from the diodes is supplied with ground potential.